cul vs dead end

cul and dead end both are nouns.

Word	Noun	Adjective	Verb	Adverb
cul	Yes	No	No	No
dead end	Yes	No	No	No

As nouns, cul and dead end are synonyms defined as:

Other synonyms of cul include cul de sac.

cul (noun)	dead end (noun)
a passage with access only at one end	a passage with access only at one end
	a situation in which no progress can be made or no advancement is possible